A support matrix of this type is known from GB Pat. No. 1 452 982.
In this known support matrix, the individual layers of steel panels can be welded together. The support matrix itself can be retained in a jacket by holding means, preferably disposed in front of the end of the matrix, this holding means consisting for example, of intersecting struts, wires, or rods, or a wire mesh.
Welding the individual layers of steel paneling is a costly procedure. The holding means at the ends of the matrix do not always suffice to prevent a mutual axial displacement of the individual layers of the steel panels in the matrix.
In a related patent, U.S. Pat. No. 4,152,302, the contents of which are herein incorporated by reference, it had been proposed to prevent the axial displacement of the layers within the support matrix as well as to provide for turbulence of gases in the channels of the matrix by fabricating at least one steel panel or steel strip of the matrix with projections and/or depressions. In particular, the depressions were to be embodied as holes or openings in the smooth steel panel only. Alternatively, the holes might be placed exclusively in the corrugated steel panels.